Function server_mpvio_read_packet

sql/sql_acl.cc:14730–14822

vio->read_packet() callback method for server authentication plugins This function is called by a server authentication plugin, when it wants to read data from the client. It transparently extracts the client plugin data, if embedded into a client authentication handshake packet, and handles plugin negotiation with the client, if necessary. */

  with the client, if necessary.
*/
static int server_mpvio_read_packet(MYSQL_PLUGIN_VIO *param, uchar **buf)
{
  MPVIO_EXT * const mpvio= (MPVIO_EXT *) param;
  MYSQL_SERVER_AUTH_INFO * const ai= &mpvio->auth_info;
  ulong pkt_len;
  DBUG_ENTER("server_mpvio_read_packet");
  if (mpvio->status == MPVIO_EXT::RESTART)
  {
    const char *client_auth_plugin=
      ((st_mysql_auth *) (plugin_decl(mpvio->plugin)->info))->client_auth_plugin;
    if (client_auth_plugin == 0)
    {
      mpvio->status= MPVIO_EXT::FAILURE;
      pkt_len= 0;
      *buf= 0;
      goto done;
    }

    if (mpvio->cached_client_reply.pkt)
    {
      DBUG_ASSERT(mpvio->packets_read > 0);
      /*
        if the have the data cached from the last server_mpvio_read_packet
        (which can be the case if it's a restarted authentication)
        and a client has used the correct plugin, then we can return the
        cached data straight away and avoid one round trip.
      */
      if (Lex_ident_plugin(Lex_cstring_strlen(client_auth_plugin)).
            streq(mpvio->cached_client_reply.plugin))
      {
        mpvio->status= MPVIO_EXT::FAILURE;
        pkt_len= mpvio->cached_client_reply.pkt_len;
        *buf= (uchar*) mpvio->cached_client_reply.pkt;
        mpvio->packets_read++;
        goto done;
      }
    }

    /*
      plugin wants to read the data without sending anything first.
      send an empty packet to force a server handshake packet to be sent
    */
    if (server_mpvio_write_packet(mpvio, 0, 0))
      pkt_len= packet_error;
    else
      pkt_len= my_net_read(&ai->thd->net);
  }
  else
    pkt_len= my_net_read(&ai->thd->net);

  if (unlikely(pkt_len == packet_error))
    goto err;

  mpvio->packets_read++;

  /*
    the 1st packet has the plugin data wrapped into the client authentication
    handshake packet